The invention relates to a process for the preparation of one or more atmospheric hydrocarbon oil distillates from a hydrocarbon oil residue obtained by vacuum distillation.
In the atmospheric distillation of crude mineral oil, as applied on a large scale in refineries for the preparation of atmospheric distillates, a residual oil is obtained as a by-product. To increase the yield of atmospheric distillates from the crude oil concerned, a vacuum distillate can be separated from the said residual oil by vacuum distillation, which vacuum distillate can be converted in a relatively simple way, for instance by catalytic cracking or hydrocracking, into one or more atmospheric distillates. Just as in atmospheric distillation, a residual oil is obtained as a by-product in vacuum distillation. In some cases this residual oil, which as a rule contains considerable quantities of sulphur, metals and asphaltenes, is only suitable for use as a fuel oil component.
In view of the increasing demand for atmospheric distillates, attempts were made in the past to convert the vacuum residues into atmospheric distillates, for instance by catalytic cracking or hydrocracking. The use of the vacuum residues as such as the feed for these processes has serious drawbacks which preclude their application on a commercial scale. Thus, major drawbacks of, for instance, catalytic cracking of the vacuum residues are that it entails very high catalyst consumption and that because of the very high coke and gas production only a low yield of the desired atmospheric distillates is obtained. Hydrocracking of the vacuum residues involves a rapid catalyst deactivation, a high gas production and a high hydrogen consumption.
To increase the yield of atmospheric hydrocarbon oil distillates from the crude oil concerned, one might consider deasphalting the vacuum residues mentioned so as to separate a deasphalted oil, which may be converted, for instance by catalytic cracking or hydrocracking, into one or more atmospheric hydrocarbon oil distillates. A drawback of this route is, however, that deasphalting of the vacuum residues yields asphalt as a by-product. Apart from its use for engineering purposes, for instance in road-building and as a component for refinery fuel, this material has only limited applicability. Conversion of the asphalt into atmospheric distillates via the above-mentioned catalytic cracking or hydrocracking processes cannot be considered in view of its very high metal and asphaltenes content. Application of other conversion processes such as coking, thermal cracking and gasification in combination with hydrocarbon synthesis is rather unattractive in view of the low yield of the atmospheric distillates mentioned and/or the high costs involved in the process.
In view of the above and considering the fact that in the processing of crude mineral oil into atmospheric distillates via atmospheric distillation, vacuum distillation combined with conversion of the vacuum distillate and deasphalting combined with conversion of the deasphalted oil, considerable quantities of asphalt are obtained as by-product, it will be clear that there is an urgent need for a process which offers the possibility of converting this asphalt in an economically justifiable way into atmospheric distillates such as gasolines.
Since catalytic cracking and hydrocracking have proved in practice to be excellent processes for the conversion of vacuum distillates such as vacuum gas oils into atmospheric distillates such as gasolines, the applicant has carried out an investigation to find out to what extent these processes can be utilized in the conversion of the above-mentioned asphalt. It has been found that a certain combination of catalytic cracking and/or hydrocracking with a catalytic hydrotreatment and deasphalting, a process can be realized that is highly suitable for this purpose. The present patent application relates to such a process.